The prevalence of headache in children and adolescents continues to rise. International studies have documented this trend (1, 2). In addition, it is assumed that headache symptoms persist into adulthood in a relatively high percentage of cases (about 50%) (3). Recurrent headaches in particular are considered to come about not only as a consequence of pathophysiological mechanisms, but as a multifactorial event (4) in which psychosocial components also play a role. The study of potential risk factors for the initial appearance (incidence) and maintenance of headaches in children is, therefore, of obvious importance. The results of the studies that have been performed to date are comparable to no more than a limited extent, because of considerable methodological differences and deficiencies. Furthermore, only a handful of longitudinal studies have been carried out on this subject in Germany until now (5, 6), often involving only a small number of cases. These reasons provided the motivation for the present longitudinal epidemiological study, called "Children, Adolescents, and Headache" (in the original German: Kinder, Jugendliche und Kopfschmerz, abbreviated KiJuKo). The primary objective of this large-scale research project is to identify the psychosocial risk factors for headache in children and adolescents. A large number of variables were tested in the study. For the purposes of this article, the variables concerning the child’s family and leisure activities were selected (table 2), because the published literature indicates that these factors are involved in headache. Family problems are often said to provoke headache (7, 8); for example, children with frequent headaches report quarreling in the family much more frequently than healthy children of the same age (age-matched controls) (9). Parental behavior when the child complains of headache seems to play a major role as well. Positive or negative reinforcement is given, through which the child learns that illness behavior confers certain advantages or privileges (10). Learning theory implies that reinforcement of this kind leads to the more frequent appearance of headache-related behavior. Table 2 Description of the dependent variables of the 2nd wave (criterion) and the tested risk factors of the 1st wave (predictors) Leisure activities also seem to affect the frequency of headache. It has been shown, for example, that children who suffer from headache at least once per month tend to be more active (i.e., are more likely to participate in sports) than children in the control groups without headache (11). The relevance of friends and social relationships to psychophysiological health has been pointed out by multiple authors. Children with weekly headaches are said to have fewer friends than children of the same age without headaches (12). Children with headaches, compared to those without, also spend more time per day watching television (9) or using a computer or game console (13). Each one of these factors can be interpreted as a type of psychosocial stress. Waldie, in a prospective study (14), showed that intense stress during puberty—operationalized with reference to various stressful events, e.g., conflict with parents—increases the probability of migraine in early adulthood. There is thought to be a two-way interaction between stress and headache (15), in which the cause-and-effect relationship remains unclear (16). Headache itself can be experienced as a stressor (17), but a variety of potential stressors can also contribute to the causation of headache. Research findings on the subject until now do not permit any conclusion as to whether the psychosocial factors studied promote the development of headache, are themselves a consequence of headache symptoms, or possibly both. The purpose of this article is to study the potential causes of headache with a unidirectional analytical approach. In the long term, the findings of longitudinal studies such as this one may contribute to appropriate modifications in existing prevention programs and therapeutic measures and to the development of new ones.